American eels — a slippery subject

Biological Bits

May 23, 2014

In a recent column about fish migrations, the American eel, scientifically called Angullia rostrata, was mentioned for its long distance movement and direction of travel. So, let's explore the life history, biology, and physical characteristics of this unique fish. This will, hopefully, clear up the differences between eels and lampreys. Too often the incorrect term "lamprey eel" is used in describing one or the other, or both, which will now be clarified.

Lampreys do not have jaws, but rather a funnel-like sucking mouth. Eels have jaws with sharp teeth and bite. Most of us have seen photos of moray eels and their impressive teeth. Simple way to remember the difference is eels bite and lampreys suck.

Worldwide there are 800 species of eels, most of which live in salt water. They vary in size from two inches to 13 feet (giant moray). The heaviest is the European conger, which grows to 10 feet and 240 pounds. Almost all eels are nocturnal, feeding at night.

There are 19 species of fresh water eels, with the American eel the only species in North America. The native range of the American eel is the east and south coasts of North America and all accessible lakes and streams. In the Mississippi River drainage, they are found north into Minnesota and South Dakota. They have expanded their range over time, and are now found in all of the Great Lakes, being native to only Lake Ontario. The nearest documented catch of an American eel is the Ontonagon River mouth.

Eels have a long, slender snake-like body, with very fine scales, but are covered with mucus, making them feel very slippery. They have a dorsal (back) fin which is connected to the caudal (tail) fin and pectoral (by the head) fins. Females are larger than males, being up to five feet long (average 3 feet) and 5-7 pounds in weight. Males average 1.5 feet and 2-3 pounds. They breathe not only through their gills, but can absorb oxygen through their skin and have been found moving overland.

An eel's diet involves almost anything that moves, including fish, clams, snails, crayfish, insects, and plants. They are nocturnal, feeding almost exclusively at night. Other fish, eagles, and herons do prey on them, especially when young.

American eels have a very complicated and unusual life cycle. They are unique in that they are the only fish in North America that are what biologists call catadromous, which means they move from fresh water to salt water to spawn. Adult eels leave rivers and streams and migrate south to the Sargasso Sea, which is 3,725 miles from the St Lawrence Seaway, making them the champs of long distance spawners. Here they deposit between 500,000 and 4 million eggs, with the largest females laying up to 8.5 million. The peak spawning takes place February to March, after which the adults die. The free floating eggs hatch in a week and begin drifting north in the warm current. During the first life stage, they are called leptocephali (leaf-like) and lasts7-12 months, as they continue drifting north. They then become glass eels, so called as they are clear and are 2-3 inches long. In about two months they get adult coloration and arrive at tidal stream mouths. This third life stage is called elvers, lasting 3-12 months as they migrate up rivers and streams. Here they remain for 10-20 years before becoming sexually mature and embark on their thousands of miles journey. American eels are long lived, with one in captivity reaching 88 years of age.

Eels are an important food source worldwide, especially in Asia, but are eaten in Europe and North America. Lake Ontario has an economically important commercial eel fishery. American eels are considered a delicacy when smoked. The eel sushi this author had was good when a sufficient amount of wasabi was added.

Fishing for American eels is permitted and is called sniggling. Sniggle is defined as a type of fish hook used for catching eels. The fishing line is tied to the middle of a needle, which is inserted into a night crawler or other bait. This is then placed near holes or suspected eel haunts. Once the eel takes the bait and after a minute or two wait, the line is retrieved causing the hook to turn sideways and the fight is on. Bon appetit!